C# Function Development

Function Syntax

You are advised to use .NET Core 3.1.

FunctionGraph supports C# (.NET Core 2.1) and C# (.NET Core 3.1).

Scope Return parameter Function name (User-defined parameter, Context)

• Scope: It must be defined as public for the function that FunctionGraph invokes to execute your code.
• Return parameter: user-defined output, which is converted into a character string and returned as an HTTP response.
• Function name: user-defined function name. The name must be consistent with that you define when creating a function.

  In the navigation pane on the left of the FunctionGraph console, choose Functions > Function List. Click the name of the function to be set. On the function details page that is displayed, choose Configuration > Basic Settings and set the Handler parameter, as shown in Figure 1. The parameter value is in the format of index.handler. The values of index and handler can be customized.

  Figure 1 Handler parameter
  
• Event: event parameter defined for the function.
• context: runtime information provided for executing the function. For details, see the description of SDK APIs.

  The HC.Serverless.Function.Common library needs to be referenced when you deploy a project in FunctionGraph. For details about the IFunctionContext object, see the context description.

  When creating a C# function, you need to define a method as the handler of the function. The method can access the function by using specified IFunctionContext parameters. Example:

  1 2 3 4

  public Stream handlerName(Stream input,IFunctionContext context) { // TODO }

Function Handler

ASSEMBLY::NAMESPACE.CLASSNAME::METHODNAME

• ASSEMBLY: name of the .NET assembly file for your application, for example, HelloCsharp.
• NAMESPACE and CLASSNAME: names of the namespace and class to which the handler function belongs.
• METHODNAME: name of the handler function. Example:

  Set the handler to HelloCsharp::Example.Hello::Handler when you create a function.

SDK APIs

• Context APIs

  Table 1 describes the provided context attributes.

  Table 1 Context objects

  Attribute	Description
  String RequestId	Request ID.
  String ProjectId	Project Id
  String PackageName	Name of the group to which the function belongs.
  String FunctionName	Function name.
  String FunctionVersion	Function version.
  Int MemoryLimitInMb	Allocated memory.
  Int CpuNumber	CPU usage of a function.
  String Accesskey	Obtains the AK (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function. NOTE: FunctionGraph has stopped maintaining the String AccessKey API in the Runtime SDK. You cannot use this API to obtain a temporary AK.
  String Secretkey	Obtains the SK (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function. NOTE: FunctionGraph has stopped maintaining the String SecretKey API in the Runtime SDK. You cannot use this API to obtain a temporary SK.
  String SecurityAccessKey	Obtains the SecurityAccessKey (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.
  String SecuritySecretKey	Obtains the SecuritySecretKey (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.
  String SecurityToken	Obtains the SecurityToken (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.
  String Token	Obtains the token (valid for 24 hours) with an agency. If you use this method, you need to configure an agency for the function.
  Int RemainingTimeInMilliSeconds	Remaining running time of a function.
  String GetUserData(string key,string defvalue=" ")	Uses keys to obtain the values passed by environment variables.

• Logging APIs

  The following table describes the logging APIs provided in the C# SDK.

  Table 2 Logging APIs

  Method	Description
  Log(string message)	Creates a logger object by using context. var logger = context.Logger; logger.Log("hello CSharp runtime test(v1.0.2)");
  Logf(string format, args ...interface{})	Creates a logger object by using context. var logger = context.Logger; var version = "v1.0.2" logger.Logf("hello CSharp runtime test({0})", version);

Execution Result

The execution result consists of the function output, summary, and log output.

{
    "errorMessage": "",
    "errorType": ""
}